The present invention relates to a centrifuge having cleaning arrangement for centrifugally cleaning bio cell such as red blood cell with cleaning liquid.
A bio cell cleaning centrifuge is installed in a clinical laboratory at a hospital and a blood bank for automatically performing bio cell cleaning operation in a blood transfusion check up. As shown in FIGS. 7 and 8 in a conventional bio cell cleaning centrifuge, a drive shaft 105 extends vertically from a drive motor (not shown), and a rotor 106 is coaxially held on the drive shaft 105. The rotor 106 has an outer peripheral portion provided with a plurality of test tube holder 121 each for detachably holding each test tube 7 in which hema H is accumulated. Each test tube holder 121 is pivotally movably supported to the rotor 106 so that the test tubes 7 can be oriented toward a horizontal direction as shown in FIG. 7 because of the centrifugal force upon rotation of the rotor 106.
A decant magnet 111 is stationarily provided coaxially with the drive shaft 105 for temporarily attracting the test tube holder 121 upon application of electric current to the decant magnet 111, so that approximately vertical orientation of the test tubes 7 can be maintained as shown in FIG. 8.
A bowl 112 is provided coaxially with the decant magnet 111. The bowl 112 has a rise-up end portion to which each free end of the test tube holder 121 is abuttable when the test tube holder 121 is pivotally moved toward the horizontal direction.
Above the rotor 106, a distributor 130 is provided for distributing a cleaning liquid such as a physiological saline into the respective test tubes 7. The distributor 130 is rotatable together with the rotation of the rotor 106. A nozzle 110 is open to the distributor 130 and is fluidly connected to a cleaning liquid source through a tube 109.
In operation, the rotation of the motor is started to enter acceleration mode M1 as shown in FIG. 9. Incidentally, a horizontal axis represents a single operation cycle and a vertical axis represents a rotation number in FIG. 9. Upon actuation of the motor, the test tube holders 121 are pivotally moved toward the horizontal direction until each free end abuts the rise-up end of the bowl 112. In this case, each test tube 7 is inclined at an angle of, for example, 38 degrees from an axis of rotation of the rotor 106.
During the acceleration mode M1, physiological saline is injected into the distributor 130 through the nozzle 110, so that the physiological saline is evenly distributed into respective test tubes 7 at a timing and period indicated by a block portion T1. In this instance, hema H is agitated with the physiological saline thereby being cleaned.
Then, the motor is entered into a constant speed mode M2 for centrifugation. For example, the motor is rotated at 3000 r.p.m. for 35 seconds. In the centrifugation, hema H is deposited on a bottom of each test tube 7, whereas blood serum and other unwanted materials remain on a supernatant fluid.
At a terminal phase of the constant speed mode M2 and immediately before a deceleration mode M3, physiological saline is again distributed into each test tube 7 at a timing and period indicated by a block portion T2 in order to enhance cleaning to the bio cell. Incidentally, the distribution timing can be adjusted by an adjustable switch (not shown).
After deceleration mode M3, rotation of the motor is temporarily stopped, and electrical current is supplied to the decant magnet 111 for magnetically absorbing each test tube holder 121 thereto. As a result, each test tube 7 is directed to approximately vertical direction or −8 degrees with respect to the axis of rotation of the rotor 106.
While maintaining this magnetically attraction state, the motor is again energized and rotated at relatively low speed such as 400 r.p.m in a low speed mode M4. In this case, supernatant fluid S rises up along each wall of the test tube 43 and are discharged outwardly from each upper open end of each test tube 7. Thus, precipitated hema H only remains in the test tube 7. The cycle including acceleration mode M1, constant speed mode M2, deceleration mode M3 and the low speed mode M4 is repeated three times.
The cleaning liquid and supernatant fluid discharged from the test tubes 7 is collected onto a chamber body 118 shown in FIG. 10 provided integrally with the main casing and positioned below the bowl 112. Then, the fluid is discharged out of a main casing (not shown) of the centrifuge through a discharge opening 118a formed at a bottom of and an outer peripheral portion of the chamber body 118.
However, the overflowed liquid in the chamber body 118 is directed toward a center of the main casing because of air flow in the chamber body 118 during centrifugation as indicated by arrows in FIG. 10. That is, because of the rotation of the rotor 106, air in the chamber body 118 is urged radially outwardly. However, the air reaching the wall of the chamber body 118 is flowed along the wall of the chamber body 118 and is then directed toward the center portion of the main casing. Therefore, liquid adhered onto the wall of the chamber body 118 is directed toward the center portion, which degrade the discharging efficiency of the liquid.
Accordingly, entire liquid in the chamber body 118 cannot be discharged outside through the discharge opening 118a, but a part of the liquid may remain in the chamber body 118. Due to the remaining liquid, propergation of various germs may occur in the chamber body, and the germs may adhere to the chamber body wall to degrade flowablity of the liquid. This further promotes growth of the various germs.
If next centrifugation is performed with new bio cell while the previous liquid remains in the chamber body 118, the remaining liquid may be converted into mist during centrifugation which may be entered into interior of the drive motor and main casing. As a result, rust and corrosion may occur to reduce service life of the centrifuge. Moreover, the growth of the various germs generates stink, or may be mixed with the cleaned bio cell samples to degrade reliability of the test.
In order to avoid the above-described drawbacks, the chamber body 118 itself must be cleaned. However, the chamber body 118 is normally provided integrally with the main case in order to maintain high rigidity and high strength for the purpose of preventing broken pieces from being scattered outwardly of the main case if the rotary member such as the rotor 106 is broken, and preventing any fluid and mist in the chamber body 118 from being entered into the driving portion such as bearing portion of the drive motor. Therefore, cleaning to the chamber body 118 itself cannot be easily performed. Further, if cleaning is performed to the chamber body while the main case is fixed at its stationary position, cleaning water may be entered into the drive motor to damage to the same. If broken pieces of the test tube remains in the chamber body, operator's finger may be injured and the operator may suffer from contagion.